A new set of emerging films are being beneficially employed in the development of high density semiconductor chips such as for example high density dynamic random access memories ("DRAM") and ferroelectric random access memories ("FRAM"). These materials provide for higher capacity devices by allowing for a reduction in the size of the individual features on the memory substrate. Accordingly, enhanced profile control technologies are required.
In the past, a number of techniques have been used to obtain a desired semiconductor feature wall profile. One technique is ion milling which is classified as a physical etching method. With this technique, an ion mill beam is used to physically sputter away portions of a layer of a semiconductor device which are not desired, leaving the desired feature defining the various components and traces on the semiconductor device. While such techniques have produced desirable profiles, the disadvantage of using ion milling techniques is that the processes are slower and such techniques tend to cause the formation of veils or fences upstanding from the desired feature.
Photoresist material is to protect and define the desired features produced by the ion milling technique. Once the photoresist material is stripped away, the veils or fences remain as undesirable and difficult to remove structures.
Chemical etching is another technique employed to remove portions of a layer of a semiconductor wafer which are unprotected by photoresist material. Such methods, while providing for faster etching than provided by, for example, ion milling, do not necessary have the same profile control afforded by ion milling.
Accordingly, there is a need to provide an etching process and apparatus which quickly and accurately processes emerging films which are used in the latest semiconductor products.